How do I change the clutch master and clutch slave cylinders on a Mazda RX-7 FB?

Difficulty: Moderate
Tools Required: 8mm, 10mm, 12mm, and 17mm wrenches (a 10mm flare nut wrench is highly recommended for the hard lines), 3/8" ratchet with a 12mm socket, 10" extension, and a flex joint. Socket caps and a ratcheting wrench are very helpful for tight spaces.
Supplies: DOT3 brake fluid, clear hose for bleeding, penetrating oil (like PB Blaster), and rags.

Replacing the clutch hydraulics on an FB RX-7 is straightforward, but working under the dash is tight, and getting the correct replacement parts can be a headache.

Part Selection Warning

Getting the correct aftermarket hydraulics for the FB platform is notoriously tricky. Community consensus strongly recommends using OEM Mazda "blue-label" parts if possible, as aftermarket master cylinders (like the Exedy MC207 or MC210) are often incorrectly listed for FBs and will fail to disengage the clutch. The MC476 (S3-specific) is usually the correct hydraulic configuration ².

Additionally, some aftermarket slave cylinders ship with undersized mounting holes. If you receive one, you can carefully drill out the cast iron body to fit, but exchanging it for a verified fit (like RockAuto #2044) is the safer bet ⁵.

Step 1: Prep and Disassembly

1. Spray the hard line fittings at both the master and slave cylinders with penetrating oil.
2. Disconnect the hard line from the flex hose at the slave cylinder, and then from the body of the master cylinder. Safety Warning: Do not push the clutch pedal while the lines are disconnected, or you will spray brake fluid everywhere. Cap the open lines or cover them with a rag ¹. General Practice: Always use a flare nut wrench on brake and clutch hard lines to avoid rounding off the soft fittings.

Step 2: Remove the Slave Cylinder

1. Use your 12mm socket and 10" extension to remove the two bolts securing the slave cylinder to the transmission. Pull the slave out with the flex hose still attached.
2. Remove the flex hose from the old slave using a 17mm wrench. Ensure you keep the crush washer (or replace it).
3. Lift the rubber boot on the old slave and pull out the internal pushrod pin so you can transfer it to the new unit ¹.

Step 3: Remove the Master Cylinder

1. Move to the driver's footwell. The master cylinder is secured by two 12mm nuts. The bottom nut is easy to reach with a socket and flex joint.
2. To access the top nut, you need to remove the connecting rod. Crack the 12mm jam nut loose, then use a 10mm wrench on the rod nut to unscrew the rod from the clutch pedal assembly. Push the rod in gently and work it out of the way.
3. Remove the top 12mm nut. A socket cap driven by a ratcheting wrench is the best tool for this tight clearance ¹.
4. Pull the master cylinder out from the engine bay.

Step 4: Installation

Clean your new cylinders before installing to ensure no machining debris gets into the hydraulic system ³. Installation is the reverse of removal.

I don't have verified factory torque figures for the master or slave cylinder mounting hardware on this exact car, so do not take a hard number from me—check a factory service manual if you want the exact spec. However, standard practice here is to simply snug them evenly. Do not overtighten the slave cylinder bolts. The FB transmission housing is aluminum and will strip very easily; a light snug is all you need ¹. Make sure the pushrod pin is properly seated on the clutch fork so it doesn't shoot out during operation.

Step 5: Bleeding the System

1. Fill the master reservoir to the top with DOT3 fluid.
2. Open the bleeder screw on the slave cylinder using an 8mm wrench. Attach a clear hose to route fluid to a catch pan.
3. Reach into the car and push the clutch pedal back and forth by hand (it will not return on its own yet). Keep pumping until the pedal gets hard, which means the system is full of fluid.
4. Close the bleeder screw. Pump the pedal by foot about 20 times to build pressure and check for leaks at your fittings.
5. Crack the bleeder screw open one last time and give the pedal one full pump to push out any final air pockets, then lock it down ¹.